https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64242
Bug ID: 64242
Summary: Longjmp expansion incorrect on i386
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: wdijkstr at arm dot com
As PR rtl-optimization/64151 showed, the longjmp expansion on i386 is incorrect
if the base register is spilled. It turns out it is trivial to write an example
that reproduces this without my patch:
void
broken_longjmp(int x, void *buf[20])
{
if (x == 0) return;
__builtin_longjmp (buf, 1);
}
With -O2 this produces:
pushl %ebp
movl %esp, %ebp
movl 8(%ebp), %eax
testl %eax, %eax
jne .L5
leave
ret
.L5:
movl 12(%ebp), %eax
movl 4(%eax), %eax
movl 12(%ebp), %edx
movl (%edx), %ebp *** load new ebp
movl 12(%ebp), %ecx *** try to use old ebp
movl 8(%ecx), %esp
jmp *%eax
